1. Field of the Invention
The present invention relates to a counter ejector of cardboard sheet box-making machine, and in particular to a counter ejector of cardboard sheet box-making machine for counting and forming batches of a predetermined number of cardboard sheets which have been folded and glued after being subjected to processing such as printing, creasing, slotting, and die-cutting.
2. Description of the Related Art
A cardboard sheet box-making machine comprises a folder-gluer for folding and gluing with glue a printed or otherwise processed cardboard sheet, and a counter ejector for counting the cardboard sheets supplied from the folder-gluer, forming a batch of a predetermined number of cardboard sheets, and sending this batch to a follow-on bundler. Cardboard sheet box-making machines of this type are disclosed in JP-A-2009-51024 (having counterparts US2010/0190626A1 and EP2181952A1), JP-B-3298896 (having a counterpart U.S. Pat. No. 6,129,503A) and the like and are well known.
The counter ejector disclosed in JP-A-2009-51024 comprises a hopper on which cardboard sheets supplied from a folder-gluer are loaded, multiple ledges for separating cardboard sheets loaded in the hopper and forming batches of a predetermined number of sheets; and an elevator for raising those batches for loading. The hopper has a front contact plate for contacting the front end portion of the cardboard sheet transferred from a pair of exit rollers placed downstream from the folder-gluer; and a spanker for contacting the back edge portion of that transferred cardboard sheet and aligning the edge of the sheet. The elevator descends as the elevator loads the batch formed by the horizontal and vertical movement of multiple ledges, handing the batch over to a lower conveyor for transfer. After this handover is completed, the elevator rises to a predetermined height to load the next batch. The elevator repeats the raising and lowering motion in the vertical direction to hand over each sequentially formed batch.
In general, a cardboard sheet box-making machine follows a particular order to perform processes such as printing on multiple types of cardboard sheet having varying dimensions in the feed direction. In a counter ejector hopper, a spanker is disposed in a certain positional relationship to folder-gluer outlet rollers in order to align sheet end portions; the front contact plate is movably disposed to adjust the gap relative to the spanker in the horizontal direction according to the dimensions of the cardboard sheet supplied from the folder-gluer. This enables the hopper to load cardboard sheets while justifying edges ends, even when dimensions between cardboard sheets differ. The elevator also has a table with a width matched to the maximum dimension of the cardboard sheet which can be processed by the cardboard sheet box-making machine.
When a cardboard sheet box-making machine processes a cardboard sheet with a relatively short dimension in the feed direction, the front contact plate in the hopper of the counter ejector moves in accordance with the short dimension of the cardboard sheet so as to reduce the gap in the horizontal direction relative to the spanker.
However, in the conventional counter ejector disclosed in JP-A-2009-51024, JP-B-3298896 and the like the elevator must be stopped at a lowered position until each batch is completely handed over to a lower conveyor for feeding from the elevator table, so as not to disturb the handover of the batch. The width of the elevator table is matched to the maximum dimension of the processable cardboard sheet, therefore even when handing over a cardboard sheet batch with a relatively short dimension, the elevator has to be stopped in the lowered position for the same amount of time as the stopping time until the cardboard sheet batch with the longest dimension is handed over from the table to the lower conveyer. A certain halt time is always required at the elevator lowered position even when continuously handing over batches with small numbers of sheets of relatively short-dimensioned cardboard sheets; this makes it difficult for conventional counter ejectors to achieve high speed transfer of relatively short cardboard sheets.